Instructions

For marinade: Purée all ingredients in a blender until smooth. Put the steak in a large bowl and cover with marinade. Cover and refrigerate for at least 24 hours and up to 48 hours.

For tomato sauce: On a grill, open flame or in a 500-degree oven, burn the outside of the tomatoes and the onion. When onions cook, the layers begin to peel off. Keep peeling the layers and cooking the rest. Put the charred onion and tomato into a medium saucepot with garlic, cilantro and balsamic vinegar and heat thoroughly on low. Purée in a blender until smooth and season with salt, pepper and a pinch of sugar (if needed).